From the sixth week of life infants start to produce non-distress vocalizations during social exchange, and adults interpret these as communicative expressions. The prosodic qualities of these early vocalizations have not been extensively studied. The aim of this study was to examine some of the factors which lead "naïve" adult listeners to perceive infant vocalization as intentional on the one hand and as expressing emotion on the other hand. A sample of 24 non-distress vocalizations produced in the course of social interaction with a parent was selected for this study. Half of the vocalizations were produced by 6 week-old infants, and half by 18 week-old. The sample was also evenly distributed according to two other factors, duration (short vs. long) and continuity (continuous vs. discontinuous). Pairs of vocalizations were created by varying only one of the 3 factors (age, duration, continuity) at a time. A hundred and ten participants heard a total of 48 pairs of vocalizations presented in counterbalanced trials and were asked to determine which vocalization was more communicative and, on a separate occasion, which expressed greater emotion. Binary response choice was recorded for each stimulus and for each participant. Results show that listeners use different strategies in attributing communicative intent and emotional intensity. It also appeared that older infants' vocalizations were generally perceived as more communicative whereas longer vocalizations were perceived to convey more emotion